Concentrated brown dye solution



United States Patent 3,310,362 CON CENTRATED BROWN DYE SDLUTION NormanWilliam Fiess, East Amwell Township, Hunterdon County, N1, assignor toAmerican Cyanamid Company, Stamford, Conn, a corporation of Maine NoDrawing. Filed June 29, 1965, Ser. No. 468,150 5 Claims. (Ci. 8-79) Thisapplication is a continuation-impart of my copending application, SerialNo. 227,939, filed Oct. 2, 1962, now abandoned.

This invention relates to the provision of stable, concentrated dyesolutions. More particularly, it relates to the provision of storagestable, highly concentrated solutions of Bismarck Brown R in a mixtureof sulfamic acid and certain organic acids.

Bismarck Brown R is a known basic azo dye prepared by tetrazotizing2,4-toluylenediamine and coupling the tetrazo with 2,4-toluylenediamine.The new Color Index listsit under number C.I. 21,010 as Basic Brown 4.

Bismarck Brown R has long been used for coloring paper products. Thedyestuif is added during a wet stage in the process, to be distributedthrough the fiber mass by means of the Water carrier. Conventionally,dyes, including Bismarck Brown R, are supplied to the paper manufactureras carefully standardized powders or crystals. Rigidly controlledprocessing and inspection, plus care-fully selected shipping containers,safeguard the uniformity and solubility of these powders or crystals. Toachieve the desired color, two important dye-handling operations remainto be done at the mill: weighing the dye, and completely dissolving iteither before or during contact time with the fiber.

It is in this area that improvement is possible, and highly desirablesince weighing powders or crystals, in addition to being a timeconsuming operation, inevitably, upon each transfer of the dye fromshipping container to scale to paper pulp, produces some hazardousdusting. Moreover, use of a solid-state dyestuif requires the step ofdissolving it, which, if not substantially accomplished, results in adye-specked product of reduced quality.

Attempts to produce Bismarck Brown R in the form of non-caking, freelyflowing particles have not been successful, primarily because of theeconomics involved. Nor has the approach of preparing and shipping thedyestuff as a concentrated solution been successful. Solutions of usefuldye concentration are difficult to prepare, and when prepared, are notso unstable to shipping and storage conditions, as to not meetcommercial standards.

It is an object of the present invention to meet and.

avoid the aforementioned difficulties accompanying the use of BismarckBrown R, More particularly, it is an object of the present invention toprovide an aqueous dye solution of Bismarck Brown R which is simple tohandle on a commercial scale, is stable and, unlike powdered andcrystalline forms, also eliminates dusting problems and possiblespecking in the dye paper product. Other objects will become apparentupon a reading of the following detailed description.

In accordance With the present invention, previous difficultiesencountered in the use of Bismarck Brown R are 3,310,362 Patented Mar.21, 1967 substantially avoided by provision of an aqueous solution ofthe dyestufr" containing dissolved sulfamic acid and a 13 carbonalkanoic acid. Such solutions can be prepared in dye concentrations ashigh as about 35%. They are simply handled, pose no dusting problems,are volumetrically measured with ease, and give a dyed product free ofundissolved dye specks.

Dye solutions of the present invention are prepared by dissolvingBismarck Brown R Base in water containing sulfamic acid and an alkanoicacid having from one to three carbon atoms (i.e., formic, acetic orpropionic acids). Dissolution may be hastened by slight agitation eitherat room or slightly elevated temperature.

For good results, it is necessary to comply with certain proportionalrequirements. Solutions containing up to 35% dyestuff are obtainable anduseful, but higher concentrations, though possible, are not desirablesince such usage is accompanied by increased viscosity, restrictingfree-flow of the solution. Solutions having lower dye concentration,i.e., in the range of 1030%, particularly, 15-25%, are preferred forease of preparation and stability. Lower concentrations, i.e., from1-l0%, may be useful in some instances, but are normally not desiredbecause of the increased shipping cost per unit of dye.

At least one weight percent of Sulfamic acid for each part of aqueoussolution should be used. Up to 35 percent may be employed. For greatestnet effect, between 5 and 30%, particularly within the range of 10-20%,of the aqueous dye solution should be composed of sulfamic acid.

The range of alkanoic acid usage is about the same as Sulfamic acid. Thetotal amount of the former may be somewhat less than that of the latterand may be comprised of a mixture of two or more of formic, acetic andpropionic acids. In general, it is preferred to have about 515% of thealkanoic acid in the final dye solution.

To prepare dye solutions of higher concentration, the sulfamic acid andalkanoic acid components should be employed in the higher sectors of theabove-stated ranges. Solutions of lower dye concentrations requireproportionately lower usage of the acid components.

The invention is illustrated by the following examples and testsresults.

A series of aqueous Bismark Brown R dye solutions (Examples AI) wereprepared using the following acids:

(A) Sulfamic acid only;

(B) Formic acid only;

(C) Acetic acid only;

(D) Propionic acid only;

(E) Hydrochloric acid only;

(F) Sulfamic acid and formic acid;

(G) Sulfamic acid and acetic acid;

(H) Sulfamic acid and priopionic acid; and (I) Sulfamic acid andhydrochloric acid.

All of these solutions were made by adding the solid dye to the watersolution of the respective acid or acids with stirring and, whennecessary, warming the solution to effect solution of the dye.Equivalent amounts of total acids were used throughout. The proportionsof components in these solutions, on a parts by weight basis, are shownin Table I.

TABLE I Solution A B C D E F G H I Bismarck Brown Base 25. 25.0 25.0 24.0 25.0 25.0 25.0 25.0 25.0 Sulfamlo Acid 28, 4 15. 5 15. 5 15. 5 15.5Formie Acid 13. 5 6. 2 Acetic Acid 17. 6 8.0 Propionle Acid 21. 7 9. 9Hydrochloric Acid (20 Be.) 34. 0 15, 4 Water 46. 6 61. 5 57. 4 54. 3 41.0 53. 3 51. 5 49. 6 44.1

Totals 100.0 100.0 100.0 100.0 100. 0 100.0 100.0 100. 0 100.0

It was found that two of these solutions, i.e., Solution E, preparedfrom hydrochloric acid alone, and Solution It will be appreciatedfurther that the combination of sulfamic acid with higher carboxylicacids would have I, prepared using sulfamic acid and hydrochloric acid,deficiencies which would make them unattractive even it formed a solidprecipitate, which appeared to be crysthey should form stable dyesolutions. For example, the tals of the dye salt, on standing for only afew minutes. unpleasant odor associated with butyric acid would pre-Also, Solution P p from Proprlonic acid y, elude its use on a commercialbasis. began to develop an insoluble material after standing for Iclaim. several days. This material, believed to be a decompo- 1 A d 1 hsition product of the dye, continued to form and settle n aqueous ye soutlon compnsmg on a wel'g t out of the solution on further standing.basls of Cl 1020% of 5111- Samples of the other solutions, A-C and F-H,which famic acid, and (c) 5-15% of an alkanoic acid of l3 did notdevelop solid matter but which exhibited an incarbon atoms crease invlscosity on standing, were sub ected to storage 25 2 The Solution ofClaim 1 wherein the alkanoic acid tests as follows. Each sample wasanalysed spectrophotometrically for strength and (except in the case of15 form; acid" Solution H) the viscosity thereof determined (a) on the3. The solution of claim 1 whereln the alkanoic acid day of preparation(b) after 1 week and (c) after 1 i ti a id, month of Storage atFOOmtemperatureh results of 4. The solution of claim 1 wherein the alkanoieacid these tests are glven m Table II. No viscosity measure- IO ioniacid ments were made on Solution H, since it was very fluid 15 P p cwhen Prepared and remained so over the entire Storage 5. The solution ofclaim 1 wherein the alkanoic acid period. is a mixture of l-3 carbonatom alkanoic acids.

TABLE II Solution A B 0 F G H Initial:

Strength, percent 52 48 50 47 49.5 52.8 Vliiscosity, cps. (21 0.)....2,350 1,010 580 1,265 750 e I Strength, percent 1 52 46 49 47 50.Viscosity, cps. (21 C.) 12, 410 8, 040 9, 110 2,000 3,820 lMonth:

Strength, percent 1 51.9 44 44.9 46.7 50 50.8 Viscosity, ops. (21 C.)16,100 12,100 9,600 2, 400 4,400

1 Relative to a commercial dye as standard.

It will be seen from Table II that Solutions A-C, pre- References Citedby the Examiner pared using only a single acid, i.e., sulfalnic acid,formic 50 FOREIGN PATENTS acid and acetic acid, respectively, exhibitedmarked in- 495,782 9 g Great i i ccregses 1n viscosity;1 on tsltan dingandflihat Solutions B and OTHER REFERENCES ecrease slgm g s reng d 55Diserens: Chemical Technology of Dyeing and Print- On the 9 F and GPrepare: utimg ing, vol. 2, 1951, pp 98-99, pub. by Reinhold Publishingsulfamic acid in combination with formic and acetic acids, Corp NewYork, respectively showed good strength retention and only Colour Index:1956 ed., vol. 2, p. 2894, Entry C.I. relatively low viscosityincreases. The solutions and 21,0103, P 1 C wl elll, Masls.650 E BSolution H are, therefore, entirely satisfactory for use C0101 Index1956 ntry asw as dye solutions, whereas Solutions A-C are not. Also,Solutions D, E and I, which developed insolubles as previouslydescribed, are obviously not suitable for this use.

Brown 4.

Cupery, Ind. & Eng. Chem, July 1942, pp. 792-797.

NORMAN G. TORCHIN, Primary Examiner.

I. TRAVIS BROWN, HERBERT, Assistant Examiners.

1. AN AQUEOUS DYE SOLUTION COMPRISING ON A WEIGHT BASIS (A) 10-30% OFC.I. 21,010, (B) 10-20% OF SULFAMIC ACID, AND (C) 5-15% OF AN ALKANOICACID OF 1-3 CARBON ATOMS.